For low-complexity or low-cost user equipment, a bandwidth that is used for receiving/sending a signal and can be supported by the user equipment is less than a maximum carrier bandwidth specified in a system or a particular carrier bandwidth. For example, in an existing long term evolution (LTE) communications system, six system bandwidths: 1.4 megahertz (MHz), 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz are specified. However, the bandwidth supported by the low-complexity or low-cost user equipment is less than 20 MHz. For example, a signal (radio frequency and/or baseband) bandwidth that can be supported by the low-complexity or low-cost user equipment is 1.4 MHz or N (N is a positive integer, for example, N=6) physical resource blocks (PRB). For convenience, a frequency resource that can be supported or processed by the low-complexity or low-cost user equipment may be referred to as a subband (in the present invention, the subband may be a narrowband). The subband refers to a frequency resource that occupies a particular frequency width on a carrier. The subband may be composed of one or more PRBs, or may be composed of one or more subcarriers. A frequency resource width and a frequency resource location of the subband are predetermined or preconfigured.
When a service is provided for the low-complexity or low-cost user equipment, the low-complexity or low-cost user equipment may receive information on multiple different subband resources. For example, multiple subband resources are configured on a carrier for the low-complexity or low-cost user equipment. System information is transmitted on a subband resource 1, and proprietary data of the user equipment is transmitted on a subband resource 2. Therefore, the user equipment may need to receive the information on the subband resource 1 and on the subband resource 2.
At a same moment, low-complexity or low-cost user equipment can receive or send information only on one subband resource because of capability limitation. The subband resource herein may be one subband resource in multiple subband resources. The information includes control information and data information scheduled by using the control information. The control information may be classified into common control information and unicast control information. The data information is classified into common data information and unicast data information according to different control information for controlling scheduling of the data information. On a control channel, if a subband resource occupied for transmitting the common control information is different from a subband resource occupied for transmitting the unicast control information, the low-complexity or low-cost user equipment cannot simultaneously receive the common control information and the unicast control information, but can choose to receive only the common control information or the unicast control information.
In the prior art, before receiving control information, user equipment needs to perform blind detection on a control channel. To reduce complexity of performing blind detection on the control channel by the user equipment, user-equipment-specific unicast control information is transmitted in a first subframe, and common control information is transmitted in a second subframe. The first subframe and the second subframe do not overlap in time. Because the common control information and the user-specific unicast control information are not transmitted in a same subframe, the user equipment does not need to simultaneously receive the common control information and the user-specific unicast control information.
The foregoing method can only ensure that common control information and unicast control information are not simultaneously transmitted, and user equipment does not need to simultaneously receive the common control information and the user-specific unicast control information. However, when data information scheduled by using control information and the control information are not transmitted in a subframe, the user-specific unicast data information and the common control information may be simultaneously transmitted, common data information and the user-specific unicast control information may be simultaneously transmitted, or the unicast data information and the common data information may be simultaneously transmitted. When the simultaneous transmission occurs, a problem about how to enable low-complexity or low-cost user equipment to receive information cannot be resolved in the prior art described above.
In addition, according to the method in the prior art, all user-equipment-specific unicast control information cannot be transmitted in a subframe the same as that in which common control information is transmitted. This greatly limits using of system resources. For example, in a coverage enhancement scenario, control information needs to be repeatedly transmitted multiple times to enhance transmission reliability. According to the method in the prior art, common control information or user-specific unicast control information can be transmitted only in a particular subframe set. As a result, a transmission resource cannot be fully used, a time consumed to transmit the control information is prolonged, and power consumption of detecting a control channel by user equipment is increased.